no, it doesnt matter when you charge the battery... draining it completely and charging it actually ruins the battery... here are some common FAQs about our batteries... Thanks BerrReview

xxx8226; They have no memory effect, which means that you do not have to completely discharge them before recharging.
xxx8226; In fact if you completely discharge the battery you are actually ruining it!
xxx8226; They start degrading as soon as they leave the factory. They will only last two or three years from the date of manufacture whether you use them or not. This is sped up even further if they are stored at high temperatures.
xxx8226; If you are buying a new battery pack, you want to make sure it really is new. If it has been sitting on a shelf in the store for a year, it wonxxx8217;t last very long. Manufacturing dates are important.
xxx8226; A lithium-ion battery pack loses only about 5 percent of its charge per month, compared to a 20 percent loss per month for NiMH batteries.
xxx8226; There is a little computer in the battery which will shut down the battery if it is completely discharged or gets too hot. This computer eats the 5% every month.
xxx8226; There is a small chance that, if a lithium-ion battery pack fails, it will burst into flame.